Conventional food preparation through heating has many inefficiencies, including the risk of undercooking, overcooking, or burning the food; all of which can lead to significant waste. Much of the effort that goes into preparing foods, especially meats, is directed to achieving an accurate temperature. In the case of foods such as chicken the accurate temperature is a necessity as illness can result from allowing people to consume the undercooked meat. However, conventional temperature measurement requires puncturing the outer layers of the flesh of the food to insert a thermometer in order to get an accurate measurement of the interior temperature of the food, to ensure thorough and complete cooking.
Sous-vide (under vacuum) cooking is a more recent development in food preparation. Sous-vide preparation involves placing a portion of food and associated spices or marinades in a flexible package and removing the air from the package and sealing the food under vacuum. The package is then placed in a bath of predetermined temperature for a set amount of time. Advantages of this type of preparation include the fact that overcooking of the food is very difficult. In conventional food preparation the cooking surface is much hotter than the desired temperature of the food—thus the food continues to increase in temperature and it is up to the food preparer to determine when the appropriate temperature has been achieved. Whereas in sous-vide preparation the bath is kept close to the desired food temperature and the food must simply remain in the bath long enough to reach the bath temperature, then the food will cease to increase in temperature as there is no thermodynamic motivation to drive more energy into the food. Thus, with sous-vide preparation accurate temperatures are achieved without the risk of overcooking the food. However, with the risks of, for example, serving undercooked food to patrons, vendors who serve sous-vide prepared dishes continue to check the internal temperature of their foods in order to prevent serving underprepared food. This often involves puncturing the sealed package and inserting a thermometer, much as before. Although necessary, this practice reduces the quality of the served food and, should the food be found to be undercooked, reduces the efficiency of reheating the food to achieve the desired temperature.
Conventional sous-vide cooking technique requires a method relating to the timing and the determining of when the contained items have reached its optimal temperature. Currently, there are only two methods in use to determine when the object to be cooked has completely its operation:
The size, shape, weight, density and starting temperature is examined in order to determine the amount of time necessary to reach the desired temperature. The sealed container is then lowered into the water bath and held there until the calculated amount of time has elapsed.
A temperature probe is inserting into the object that is to be heated, in order to measure the temperature during the cooking process and determine with the cooking process has completed. Since the object to be cooked in contained within a vacuum sealed container, this temperature probe must not be inserted in such a way as to disturb the vacuum seal of the container.
These two methods for determining cooking time present several issues:
The time calculation requires a great deal of careful and skilled calculation in order to properly estimate the amount of necessary time. Since this issue can be quite difficult, depending upon the shape of the object, the sous-vide process operator can overcome this issue, by extending the time longer than truly necessary. While this solution produces reasonable results, it has the disadvantage of affecting food flavor and tying up value resources that can be used for further food processing.
The temperature probe can be problematic, as the contained object must continue to be held under a vacuum seal while the probe is inserted. While that can be accomplished by the use of an external air tight material, the technique is highly prone to error. Furthermore, the use of several temperature probes within the same sous-vide water bath creates a greater likelihood of vacuum failure.